At such bench seats for motor vehicles, in particular in the field of camping cars, lap belts are still often used as safety belts (two-point safety belts), though in the field of passenger cars the three-point safety belt long ago succeeded as the optimum retaining device. One reason is that the bench seat frames do not offer sufficient stability for an articulation of three-point safety belts, in particular with the top coupling point (return point of the belt). An articulation of the safety belts at the so-called B- or C-column of the vehicle body, as this is usual in the field of passenger cars, is out of question due to two reasons. Often, the bench seat is arranged in a spaced manner to a side panel of the vehicle body to create sufficient passages for the living space of the camping car. Thus, the top coupling point for the central seat position has to be guided for a long distance of about 1 m up to the next beam of the vehicle. The second reason is that in camping cars only plastic built-ons without a particular rigid structure of the body are often built up onto a vehicle chassis, such that in case of an articulation at these built-ons, the required security in case of an accident, in particular the tear resistance of the top return/coupling point is not appreciable. Also, the solution known from various vans, according to which the top coupling point of the safety belts is arranged at the ceiling (roof) is not practicable for camping cars, because a sufficient standing height and, thus, a great distance between bench seat and vehicle ceiling would be required.
DE 93 02 831 U1 discloses a bench seat comprising a vertical support being mounted on the floor portion of the vehicle chassis. In addition, this vertical support is laterally supported by the back rest and by a horizontally extending traverse. Moreover, only one safety belt is completely arranged at the bench seat frame whereas the top coupling point of the second safety belt is arranged at a side panel of the vehicle. Therefore, a rigid outer body is required which is in general not available with a camping car comprising a plastic body. Moreover, the arrangement of the bench seat is constructively defined by this and cannot be pushed away from the top belt coupling point of the outer seat, as this would be convenient for the production of camping cars with a variable and often differing bench seat arrangement.
DE 79 23 386 describes a single seat with triangularly arranged stiffening braces being articulated at the base portion of the seat.
DE 21 13 579 discloses a holding device for safety means, with steadying struts being directly mounted on the vehicle floor. However, this requires an additional cross-strut for anchoring at the lateral beams of the chassis.
From U.S. Pat. No. 2,740,642 and DE 27 47 398 there are known retaining systems with upright tubes behind both front seats, with the tubes being clamped between vehicle floor and vehicle ceiling for an additional fixing or being mounted by a wire rope. This requires a rigid structure of the ceiling which is in general not available with camping cars.
DE 91 14 531 deals with an anchoring frame for bench seats being stiffened by respective braces. However, conventional two-point (lap) belts are provided with this.
DE 40 03 941 relates to a safety belt arrangement for back seats with the top coupling point of the three-point safety belt being mounted on a steady component part behind the back seat unit.
U.S. Pat. No. 3,451,719 merely shows a bar for tightening lap belts extending crosswise behind a bench seat.
U.S. Pat. No. 2,833,554 describes a bounce safety system with a shielding plate being provided in front of the driver's chest and knees and being supported at a central bar which is mounted on the body ceiling and on the floor.
U.S. Pat. No. 2,891,804 refers to a support device of an obliquely extending two-point belt, with a column being mounted on the vehicle ceiling and an additional strut being inserted into the ceiling.
UK 2 102 743 deals with a holding device for wheelchair drivers in buses with the columnar bars being again braced between floor and ceiling.